Key frames don't paste and flip properly or at all in dope sheet
Not sure if answering my own question is allowed but maybe this will help someone figure out what's wrong with their rig if they come accross this issue.

So it turns out that for my specific case I had the arm and leg bones directly connected to the spine by another bone (clavicle and hip bones) which somehow messed with the ability to flip a set of keyframes. So I remade the armature from scratch with the same bones and had the arm and leg bones separate but still parented to the spine and it all flipped perfectly fine. I found a lack of memory also prevented a certain amount of keyframes from being flipped, so the less bones to animate the smaller the chance you'll get this bug.